96 POLLEN-COLLECTORS OF CAMPANULA. 
bi 
extremely delicate structure, the least pressure causing a displace- 
ment of the loose particles (termed cambium globulo-cellulaire by 
Mirbel and Spach) and a movement along the central canal; more- 
over, the parts are soon ruptured or greatly altered in appearance 
by endosmosis, while the dissection is under examination in water. 
It appears to me, that neither Schleiden, nor Mirbel and Spach have — 
rightly interpreted the organ under consideration ; and that nothing 
positive has been advanced on either side of the question. 
Mirbel and Spach mention a curious fact which has escaped the 
observation of Schleiden, viz., “the double point formed by the 
primine and secundine within the canal of the ovary." I find 
something even more curious than they appear to have noticed, 
viz. the erect position of the primine, having its foramen at the 
very summit, within the canal of the ovary, far removed from the 
foramen of the secundine, which has accompanied the nucleus, 
pari passu, throughout its campylotropous development, and is 
found immediately in front of the so-called wtricule primordiale ; 
so that the pollinie tube (which I have not yet had the opportunity 
of tracing in its progress) would appear after entering the primine 
to pass to the foramen of the secundine by no definite course ; and 
a special provision seems to have been made in the narrow repli- 
cation of the secundine (or possibly a distinct additional membrane) 
which passes all round the base of the ovule within the primine, 
its margin partially covering the orifice of the secundine, thus 
forming a groove or conduit for the pollen-tube after it has tra- 
versed the interior of the primine. Mirbel and Spach lay much — 
stress upon the absence of proof of the existence of any pollen-tube 
protruding from the micropyle immediately after fecundation; but — 
it is worth while to enquire whether such proof may not be obtain- 
able, and whether it may not have been overlooked hitherto, through 
imperfect acquaintance with the structure of the ovule. The sub- 
ject certainly calls for further investigation. As to the suspensor, 
reported to have been seen by Mirbel and Spach, I would observe —— 
that whenever it is visible in the ovule of any plant, it is always in 
: immediate connexion with the embryo, or its membranous covering, . à 
_ as is exemplified in the case of Zea Mays ; if due attention be paid to —— 
E 16 and 19, which I cannot admit to be a metame rphosis ake 
